Goulds J5SH - Did I Ruin It?

I have a Goulds J5SH 1/2 hp jet pump sitting at the base of a 500 gal storage tank which is filled by a submersible pump from the well. It is connected only to irrigation. We were out of town with some freezing weather expected so I shut down both pumps and bled the lines from the pump shed to the irrigation system. When we returned two weeks later, I turned on the jet pump and started the irrigation timer. I forgot about the submersible and when the 500 gallons was used up, the pump ran continously for 36 to 48 hours until I caught it. It was pretty hot to the touch, but when I introduced water, it cooled right down and sounded totally normal thereafter.

But instead of holding 50 or so pounds of pressure while the sprinklers are running, now it is holding about 35#, although it still does recover to the 60# set limit when the spinklers are turned back off. So, did I:

1. Ruin an impeller?
2. Plug a filter I don't know about inside the pump when I sucked up the last of the water?
3. Something else?

And is there a kit I can order to get it back to normal pressures if needed? I am pretty mechanical, just unfamiliar with this pump.

Okay, lots of views but no help. How about just this, which could eliminate one possibility before I start throwing parts at the pump?

There is a brass plug in the end of the pump case. The exploded parts breakdown of the J5SH shows a "Nozzle" located behind this plug (http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/BJS .pdf), #11 on the last page. Maybe the nozzle is cloughed or has a restriction that is causing a loss of pressure. The water tank was pretty groady at the bottom with all the water pumped out. Does the brass plug hold this nozzle in place, or does it screw out with an allen wrench, or ??? How do you properly check to make sure the nozzle is clear?

I went a little farther. I pulled the pump and benched it. Broke the motor off the pump, which was easy, and inspected everything. The nozzle was totally clear. The impeller and diffuser were both in perfect shape. The only abnormality I could see was a little bellowing of the diaphram, but no tears or rips or other indications that it should not work normally. There were no indications of internal leaks, and the seal ring behind the diaphram was in good shape.

I did look for a strainer in front of the pump and there was none.

Before I disconnected the pump, I checked the cut in pressure and it was 43 (if the guage is correct). When emptied, I checked the pressure tank pressure and it was 35. Shouldn't that be about 2 # below the cut in pressure? I did note that when I turned off the 500 gallon supply tank while the pump was running, the pressure tank was completely empty and I guess that makes sense.

Just because it is on the bench opened up, I called the distributor to discuss all this and he suggested at least replacing the diaphram and oring, which I ordered. He had no other thoughts, but was surprised the impeller and diffuser were not warped from the heat buildup while running dry.

The impeller may look good, but I will bet the hub or inlet eye is gone.

Click to expand...

I believe that what you are referring to is what I know as a wear ring. That's the first thing I thought of. The "hub" of the impeller fits closely into the diffuser. Excess clearance causes internal water leakage while operating.

I wouldn't replace the diaphragm or o-ring. If they seal, that's good enough. The diaphragm is to help the pump prime itself, and it doesn't matter if it isn't perfectly flat.

It could be that there is nothing wrong with your pump and there is another reason it only holds 35psi. Like more water going to the irrigation system, or a restriction on the inlet side for whatever reason. That same diaphragm that makes priming the pump easier, also keeps some water in the pump even while "running dry".

To bad I didn't know what that diaphram was for last week. $30 for a replacement with the rubber base seal. All back together now and running perfectly, with the same pressures - no change there. The supply is from a well fed 500 gallon storage tank right next to the jet pump, which is full to no suction head and there is no shortage of inlet water. So now I am going to focus on possible restrictions or line loss in the irrigation system. I really don't think it is the pump anymore.

Most small pumps don't have wear rings anymore. The impeller hub just fits tight inside the diffuser body. Just a couple of thousands of an inch of wear between the impeller hub and diffuser and the internal leakage makes the pump loose a lot of efficiency or pressure. Basically if you can see daylight between the impeller hub and the diffuser or wear ring, the pump won't make pressure.

Most small pumps don't have wear rings anymore. The impeller hub just fits tight inside the diffuser body. Just a couple of thousands of an inch of wear between the impeller hub and diffuser and the internal leakage makes the pump loose a lot of efficiency or pressure. Basically if you can see daylight between the impeller hub and the diffuser or wear ring, the pump won't make pressure.

Click to expand...

That is good information. Interestingly, this pump is set from the factory at 30# on, 50# off. Someone before me increased the pressure and the on is 43#, off 63#. It builds to 63# without excessive running so I have to assume the pump and diffusser are in pretty good shape. Wish I had understood more about all this in the beginning. The pressures alone would have answered some questions about the pumps health.